Elastomeric compound

ABSTRACT

The subject invention reveals a method for preparing a coated fabric which comprises (I) applying a vulcanizable elastomer composition to a layer of fabric, wherein the vulcanizable elastomer composition is made by: (1) mixing a cross-linkable functionalized polyethylene with at least one cross-linkable liquid elastomer to form a non-reactive extrudant, wherein the mixing occurs at a temperature in the range of 10° F. above or below the melt point of the cross-linkable functionalized polyethylene, and wherein the non-reactive extrudant contains from 20 to 80 pph of the cross-linkable liquid elastomer, (2) extruding the non-reactive extrudant, and (3) mixing the extrudent with at least one curing agent, wherein the mixing is sufficient to form the vulcanizable elastomer which has a complex dynamic viscosity of less than 5 McP (5,000 N*s/m2) for at least 2 minutes at a maximum flow temperature; and (II) heating the layer of fabric having the vulcanizable elastomer applied thereto to a temperature which is within the range of 200° F. to 310° F. for at least 2 minutes to produce the coated fabric.

This is a divisional of U.S. patent application Ser. No. 12/706,158,filed on Feb. 16, 2010, now issued as U.S. Pat. No. 7,759,427 which is adivisional of U.S. patent application Ser. No. 11/154,776, filed on Jun.16, 2005, now issued as U.S. Pat. No. 7,683,136. The teachings of U.S.patent application Ser. No. 11/154,776 and U.S. patent application Ser.No. 12/706,158 are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention is directed to an elastomeric compound and amethod of preparing the compound. Specifically, the present invention isdirected to an elastomeric compound comprising a liquid elastomer thatis particularly useful for treating a cord or fabric that will beembedded in or attached to the surface of an elastomeric product whereinthe encapsulation of the fabric or cord within the product is improved.

BACKGROUND OF THE INVENTION

In manufacturing reinforced elastomeric products, it is essential thatthe reinforcing means adhere to the elastomer. This is conventionallyaccomplished by first treating the cord or the fabric with an adhesive,such as an RFL. The material may then be subjected to a topcoating, andeventually the cord or fabric is embedded in elastomer.

U.S. Pat. No. 6,764,422 (Hasaka et al) discloses a number of methods oftreating a fabric. The disclosed methods include various combinations ofpretreating with an epoxy compound, adhesion treating with RFLconsisting of an elastomer latex, and overcoat treating with a rubberadhesive prepared by dissolving a rubber in a solvent. While thisproduces a cord that bonds well, the adhesion treating and the overcoattreating use either latex or a solvent. When using such treatments, theliquid in the latex solution or the solvent must be evaporated orotherwise removed, creating an additional step in the fabric processingand requiring additional machinery to remove and handle the removedliquid or solvent.

The viscoelasticity of useful elastomers is somewhat reduced by heat andshear generated by calendering, but not to the same extent achieved bysolvation. The calender can apply the elastomer at higher pressure andthe softening elastomer can penetrate the larger interstices near thesurface of the fabric or cord but not the smaller interstices of thefabric or cord. Even when softened, the unvulcanized elastomer has asignificant elastic component of the viscoelasticity that reducespenetration of small cavities.

The encapsulating material on the outer surface of fabric on the surfaceof the elastomeric product may also need to have properties of oilresistance, wear resistance, ozone & heat resistance, coefficient offriction, depending on the function of the reinforced article.

SUMMARY OF THE INVENTION

The present invention is directed to an elastomeric compound comprisinga liquid elastomer. The liquid elastomer imparts a desired complexdynamic viscosity property to the elastomeric compound that renders theelastomeric compound particularly suitable for treating fabrics andcords to ensure full encapsulation of the fabrics or cords.

Disclosed herein is an elastomeric compound, the elastomeric compoundcomprising a liquid elastomer. The elastomeric material, prior to cure,has a complex dynamic viscosity of less than 5 McP (5,000 N*s/m²) for atleast 2 minutes at a maximum flow temperature T_(F). The liquidelastomer has a complex dynamic viscosity less than 5 McP (5,000 N*s/m²)at a temperature between 20° C. and the maximum flow temperature T_(F)and is present in the elastomeric compound in amounts of 20-80 parts perhundred cross-linkable material (phcm), preferably 25-60 phcm.Additionally, the elastomeric compound may have 2-15 parts per hundredof cross-linkable material of peroxide.

In another aspect of the disclosed elastomeric compound, the liquidelastomer is selected from the group consisting of butadiene rubber,NBR, HNBR, SBR rubber, neoprene rubber, butyl rubber, polyisoprenerubber, propylene rubber, XNBR, or EP(D)M rubber.

Disclosed herein is a method of forming the elastomeric compound whereinthe solid elastomer of the compound is fluxed into the liquid elastomer.This is done by mixing the at least one solid elastomer into the liquidelastomer at a temperature in the range of 10° F. (5.5° C.) above orbelow the melt point of the solid elastomer. The elastomers are mixed toform a non-productive that is then extruded. The extrudant is mixed withcuring agents, and other elastomeric additives as necessary, to form avulcanizable elastomer.

Disclosed herein is a method for treating fabric or cords for use in areinforced elastomeric article using the elastomeric compound. Thereinforced article may be a hose, belt, tire, air spring sleeve, orother article. After the mix of solid and liquid elastomers is mixed toform a vulcanizable elastomer, the material is applied to a fabric orcords. The coated fabric or cords is heated to a temperature of 200°F.-310° F. (93° C.-154° C.) for at least two minutes wherein theelastomer fully penetrates the fabric or fully encapsulates the cords.This heating may occur prior to forming the uncured reinforced articleor may occur in a mold or autoclave prior to curing the article.

Additionally, the fabric or cords may be pretreated with an adhesive.When coating fabrics, the treated fabric may comprise more than onelayer of fabric. The fabric may be woven, knitted, needled, matted, orcomprises a plurality of individual cords and nominal weft threadsmaintaining a spacing of the individual cords.

Disclosed herein is a power transmission product employing at least onecord or fabric layer, the cord or fabric layer being impregnated withthe elastomeric compound comprising 20-80 phcm of a liquid elastomer.The cord or fabric layer may form at least one surface layer of thepower transmission belt. The belt may be a v-belt, a poly-v belt, asynchronous drive belt, or any other type of conventional belt.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by way of example and with reference tothe accompanying drawings in which:

FIG. 1 is a v-belt;

FIG. 2 is a toothed transmission belt;

FIG. 3 is an exemplary method for applying liquid elastomer to a fabric;and

FIGS. 4-6 show dynamic viscosity properties of different compounds.

DETAILED DESCRIPTION OF THE INVENTION

The following language is of the best presently contemplated mode ormodes of carrying out the invention. This description is made for thepurpose of illustrating the general principles of the invention andshould not be taken in a limiting sense. The scope of the invention isbest determined by reference to the appended claims. The referencenumerals as depicted in the drawings are the same as those referred toin the specification. For purposes of this application, the variousembodiments illustrated in the figures each use the same referencenumeral for similar components. The structures employed basically thesame components with variations in location or quantity thereby givingrise to the alternative constructions in which the inventive concept canbe practiced.

A typical v-belt 10 is illustrated in FIG. 1. The belt 10 isparticularly adapted to be used in associated sheaves in accordance withtechniques known in the art. The belt is adapted to be used in so-calledtorque sensing drives, applications where shock loads of varying belttension are imposed on the belt, applications where the belt is operatedat variable speeds, applications where the belt is spring-loaded tocontrol its tension, and the like.

The belt 10 has at least one drive surface. In the illustrated belt,there are three drive surfaces 12, 14, 16. The belt 10 comprises atension section 18, a cushion section 20, and a load-carrying section 22disposed between the tension section 18 and the cushion section 20.

The belt 10 may also be wrapped or provided with a fabric layer 24 onall sides. The fabric layer 24 may be made from a bi-directional,non-woven, woven, or knitted fabric. Each fabric layer 24 is coated withan elastomeric material selected to assure the layer 24 is bonded to itsassociated belt section 18, 20, 22. The fabrics for use in the belt 10are made of conventional materials including nylon (such as nylon 4,6,nylon 6, 6, and nylon 6), cotton, polyester, cotton/polyester,nylon/polyester, cotton/nylon, Lycra™ (segmented polyurethane), aramid,rayon, and the like. Preferably, the fabric is made of cotton/polyester.

The load-carrying section 22 has load-carrying means 26 in the form ofload-carrying cords or filaments which are suitably embedded in anelastomeric cushion or matrix 28 in accordance with techniques which arewell known in the art. The cords or filaments may be made of anysuitable material known and used in the art. Representative examples ofsuch materials include aramids, fiberglass, nylon, polyester, cotton,steel, carbon fiber and polybenzoxazole.

The rubber compositions for use in the tension section 18 and cushionsection 20 may be the same or different. Conventional elastomers whichmay be used in one or both of these sections include natural rubber,polychloroprene, acrylonitrile-butadiene copolymers (NBR), polyisoprene,zinc salts of unsaturated carboxylic acid ester grafted hydrogenatednitrile butadiene elastomers, styrene-butadiene rubbers, polybutadiene,EPM, EPDM, hydrogenated acrylonitrile-butadiene copolymers (HNBR),polyurethane, CPE, elastomers marketed under the Viton™ designation andethylene-acrylic elastomers sold under the name VAMAC and blendsthereof. The matrix 28 may also be the same composition used for thetension or cushion sections 18, 20.

The drive surfaces 12, 14, 16 of the belt 10 of FIG. 1 are smooth. Inaccordance with other embodiments and as discussed later, it iscontemplated herein the belts of the present invention also includethose belts where the drive surface of the belt may be single V-grooved,multi-V-grooved and synchronous wherein an inner toothed surface thatengages with tooth spaces on the periphery of a mating sprocket.Representative examples of synchronous belts include belts havingtrapezoidal or curvilinear teeth. The tooth design may be perpendicularto the belt, or have a helical offset tooth design such as shown in U.S.Pat. No. 5,209,705 and U.S. Pat. No. 5,421,789. A toothed belt 30 isillustrated in FIG. 2.

The belt 30 has a belt body with an outer surface 32 and an inner facingtoothed surface 34. The inner facing surface 34 has at least one row ofadjacent rows of teeth 36. The belt body 38 is made of a resilientelastomer and preferably reinforced with longitudinal tensile members 40that lie along the belt longitudinal direction L. The outer surface 32of the belt may also be formed with teeth, forming a dual sided belting.The inner toothed surface is reinforced with an abrasion resistancefabric 42. The illustrated fabric 42 is defined by warp and weft yarns.The warp yarns 44 extend in the transverse direction T while the weftyarns 46 extend in the longitudinal direction L. Alternatively, thefabric may have the warp and weft yarns inclined at other angles, i.e. abias cut fabric, or the fabric may be a knit.

As noted above, to effectively adhere the fabric layer 24, 42 to thebody of the belt, the fabric layer is coated with an elastomercomposition. The outer surface of the fabric may also be coated toachieve resistance to oil, ozone, and abrasive wear and to control thecoefficient of friction. An elastomer may also be forced into voids ofthe fabric to encapsulate the individual fibers or fiber bundles toreduce internal wear that occurs when fibers move or flex while incontact with adjacent fibers.

High stress cycling of EP or EPDM elastomers in contact with a metalsurface can result in softening and transfer of the softened materialfrom the body of the elastomer to the metal surface. In the context ofpower transmission products, such as the belts discussed above, thisundesirable process is called piling. Since the fabric coatingelastomeric composition, after vulcanizing of the belt, forms all orpart of the driving surface of the belt, reduced pilling of the beltsurface is desired. One way to achieve a reduced pilling of the beltsurface for belts made of EP or EPDM elastomers is to have a highethylene content of the elastomeric composition, preferably greater than65%. To achieve this high ethylene content, a suitable basecross-linkable material is EPDM. However, EP(D)M compounds withrelatively high ethylene content can be difficult to process.

Increasing the ethylene content can also be achieved by the use offunctionalized polyethylene. Unvulcanized, functionalized polyethyleneis a brittle thermoplastic at room temperature, but exhibits a meltpoint below T_(F) max. Two examples of base cross-linkable materialsmixes for an elastomeric composition that result in a desired highethylene content are set forth in Table 1 below.

TABLE 1 Material A B EP¹ 25 21.5 EPDM² 25 21.5 Polyethylene³ 50 57 # allamounts are provided in parts per hundred cross-linkable material (phcm)¹Trilene CP80, liquid EPM that has an Ethylene/Propylene ratio of 43/57and has a Brookfield viscosity of 500,000 cps at 140° F. (60° C.), fromCrompton Corp. ²Trilene 77, is a solid EPDM at room temperature that hasan Ethylene/Propylene ratio of 75/25 with an ENB content of 10.5%, fromCrompton Corp. ³A-C 307A, an oxidized polyethylene homopolymer, fromHoneywell Specialty Chemicals, has a Brookfield viscosity of 85,000 cpsat 302° F. (150° C.).

Both Examples A and B above use liquid elastomers as primarycross-linkable constituents in the compound. Liquid elastomers areknown; however, such compounds are conventionally used not as a primaryconstituent in a compound but as a processing aid in conventionalamounts of generally less than 10 parts per hundred rubber (phr) toassist in incorporation of additives in a solid elastomeric compound.

In accordance with the present invention, the fabric layer is treatedwith an elastomer composition wherein the cross-linkable materialcomprising the elastomer composition includes a liquid elastomer. Theliquid elastomer is present in amounts of 20-80 phcm. Preferably, theliquid elastomer is present in amounts of 25-60 phcm. Most preferred isa liquid elastomer content of 30-55 phcm.

Cross-linkable material is herein defined as a material in a compositionthat chemically links with other material within the composition. Forthe purpose of this definition, co-agents and co-cures, such asperoxide, zinc methacrylate, zinc diacrylate, bis-maleimide, are notconsidered cross-linkable materials. Cross-linkable materials includeconventional solid elastomers, liquid elastomers, and cross-linkablethermoplastic resins or waxes.

Liquid elastomer is herein defined as an elastomer that has complexdynamic viscosity less than 5,000,000 centipoise (5,000 N*s/m²) at sometemperature between 20° C. and the maximum flow temperature T_(F) maxfor that material. T_(F) max is herein defined as the maximumtemperature at which the complex dynamic viscosity of the elastomer,when compounded for any useful purpose with vulcanizing materials andprior to vulcanization, remains less than 5,000,000 centipoise (5,000N*s/m²) for at least 2 minutes. The viscosity is measured by a RubberProcess Analyzer, Model No. 2000 by Monsanto Corporation of St. Louis,Mo., applying 0.5 degree strain at 60 cps, which results in 14% P-Psinusoidal strain and shear rate of 0.438 inverse seconds. The complexviscosity includes the elastic and viscous components of stress arisingfrom the sinusoidally imposed strain, and includes the yield stress forelastomers exhibiting plastic or Bingham flow properties. Elastomersmeeting this definition may appear to be liquid or solid at roomtemperature, but have a very low viscosity compared to elastomers whichare defined by a Mooney viscosity at a flow temperature T_(F) in therange of 200°-310° F. (93°-154° C.). The onset of vulcanization may bepresent at T_(F) max, but practical vulcanization preferably begins attemperatures T_(V) greater than 300° F. (149° C.).

FIGS. 4-6 show the complex dynamic viscosity properties, specifically,the η′, η″, and η*, of different compounds, including several thatcomprise liquid elastomer per the present invention. In the charts, thecompounds tested are as follows:

TABLE 2 Compound 1 low mooney solid EP 2 high mooney solid EPDM ACompound A from Table 1 C 50/50 phcm blend of liquid EPM and EPDMAll of the compounds had similar carbon black loading and peroxide curesystems. For testing, samples were placed in the RPA-2000 in a biconicalcavity that had been preheated to 220° F. and a sinusoidal strain ofconstant amplitude and frequency was applied as the temperature waschanged. The temperature versus time profile was:

1. ramp from 220° F. to 350° F. in 6.5 minutes;

2. cure at 350° F. for 15 minutes; and

3. cool slowly from 350° F. to 120° F.

Each test was repeated 3 times and the results averaged to determine thecompound properties. To read the charts of FIGS. 4-6 as a time-line,start at the 220° F. end of each line, follow the temperature increaseto 350° F., and subsequent decrease to 120° F. The maximum viscosity forthe T_(F) max is indicated by the MAX line.

Compounds 1 and 2 show typical low and high mooney polymers withmoderate carbon black loading. For the viscous component of the complexdynamic viscosity, η′ is relatively constant prior to cure and begins todecrease with increasing temperature until vulcanization begins. Aftercure, the material softens slightly with decreasing temperature. Theelastic component of the complex dynamic viscosity, η″, shows compounds1 and 2 decreasing slightly in elasticity with increasing temperature,and then significantly increasing as vulcanization begins. After cure,the η″ remains high and only decreases slightly, but is greater thanprior to cure.

For compound A, the curves show the much lower uncured stiffness of theliquid polymer. The compound softens quickly as it approaches the meltpoint at which point it has a much lower uncured stiffness thancompounds 1 or 2. The melt point of compound A is below thevulcanization temperature of the compound. Post cure, the compound hasdynamic viscosity properties similar to conventional elastomers.Compound C also has a relatively low viscosity prior to cure, with adynamic viscosity similar to conventional elastomers post cure.

While the above examples are specific to EPDM to achieve a high ethylenecontent for use with power transmission products, other liquidelastomers may be employed with the present invention. Suitable liquidelastomers include, but are not limited to, homopolymerization productsof butadiene and its homologues and derivatives, for example,methylbutadiene, dimethylbutadiene and pentadiene as well as copolymerssuch as those formed from butadiene or its homologues or derivativeswith other unsaturated monomers. Among the latter are acetylenes, forexample, vinyl acetylene; olefins, for example, isobutylene, whichcopolymerizes with isoprene to form butyl rubber; vinyl compounds, forexample, acrylic acid, acrylonitrile (which polymerize with butadiene toform NBR), methacrylic acid and styrene, the latter compoundpolymerizing with butadiene to form SBR, as well as vinyl esters andvarious unsaturated aldehydes, ketones and ethers, e.g., acrolein,methyl isopropenyl ketone and vinylethyl ether. Other examples ofsynthetic rubbers include neoprene (polychloroprene), polybutadiene(including cis 1,4-polybutadiene), polyisoprene (including cis1,4-polyisoprene), butyl rubber, including halobutyl rubber such aschlorobutyl rubber or bromobutyl rubber, styrene/isoprene/butadienerubber, copolymers of 1,3-butadiene or isoprene with monomers such asstyrene, acrylonitrile and methyl methacrylate, as well asethylene/propylene terpolymers, also known as ethylene/propylene/dienemonomer (EPDM), and in particular, ethylene/propylene/ethylidenenorbornene (ENB) terpolymers. Additional examples of rubbers which maybe used include a carboxylated rubber such as carboxylated NBR,silicon-coupled and tin-coupled star-branched polymers. The preferredrubber or elastomers are EP(D)M, NBR, HNBR, SBR, XNBR, and CR.

Other exemplary compositions which may be used in the disclosed methodare disclosed in greater detail in copending U.S. patent applicationSer. No. 11/026,769, filed on Dec. 31, 2004, having a common inventorwith the present application, and fully incorporated by referenceherein.

To achieve thorough mixing of the compounds wherein a substantiveportion of the cross-linkable material is a liquid elastomer and a solidmaterial is being mixed therein, the solid material is fluxed into themix. That is, the temperature of the mixture should be in the range of10° F. (5.5° C.) above or below the melt point of the thermoplasticsolid, the selected temperature of the mix is likely to be dependantupon the processing equipment. After the solid material is fluxed intothe liquid elastomers, the material is subjected to a low shear mixingoperation below the melt point of the thermoplastic solid. For solidmaterials not having a defined melt point, i.e. the material onlysoftens as heated, conventional mixing methods using banburys, kneaders,and open mills may provide for sufficient thorough mixing of thecompound.

In one sample mixing, the solid material, in the form of a powder, isadded to a twin-screw compounding extruder. The powder melts as ittravels through the extruder, and the liquid components are added intothe extruder to be mixed into the melted thermoplastic components. Heatis applied to the extruder and the mixing within the screw extruder alsogenerates heat to achieve thorough mixing of the components and fluxingin of the solid material. The non-productive mix is extruded, and theextrudant may be in the form of strings or pellets, the specificconfiguration dependent upon the machinery.

To transform the non-productive extruded material into a vulcanizablecompound, the material is placed in an extruder, a mill or other mixerand curing agents and any other additional constituents, such as carbonblack and/or silica, are added. The vulcanizable product is thenprepared to coat any reinforcing means.

To achieve a high ethylene content elastomeric compound, as desired toreduce pilling of the power transmission products, for compoundscomprising a relatively high amount of polyethylene, to achieve thenecessary cross-linking of the material, peroxide is typically used inthe cure system. For such a cure system, the amount of peroxide that isadded is in the amount of 2-15 phcm, preferably 5-15, most preferably5-10 phcm. If the peroxide amount is too great, the cross-linking willbe too great and the material will be ebonized, and the reducedelongation of the material will be detrimental to the desired productcharacteristics. The amount of peroxide employed herein is relativelyhigher than conventional, bordering on ebonizing the material; however,the slight loss of elongation of the material results in a betterwearing product. Those skilled in the art will recognize and appreciatethat the cure systems, including those using sulfur and metal oxide,used is dependent upon the cross-linking components of the compoundbeing prepared.

The coating with an elastomer comprising a liquid elastomer isapplicable to any reinforcing means for elastomeric products. Thereinforcement means may be individual cords, such as the cords 26, 40 ofthe belts 10, 30 or fabric layers such as the fabric 42 of belt 30.Thus, unless specifically mentioned otherwise, all future references tofabric include individual cords, whether provided with a nominal weftthread to maintain spacing of cords in a fabric-like manner or a singlecord.

One exemplary schematic of the coating method is illustrated in FIG. 3.After the fabric layer 50 is prepared by any conventional method suchas, but not limited to, weaving, knitting, needling, or mat preparation,the fabric layer 50 is fed into an applicator. The liquid elastomer 52,which is solid or has a very high viscosity at room temperature and hasbeen heated to a temperature below T_(F) which reduces the viscosity, isapplied to the fabric 50. The elastomer 52 is illustrated as beingapplied by passing the fabric 50 under a puddle of elastomer 52 and ablade 55 that removes excess elastomer and controls the thickness of theinitial coating layer 54. Some of the elastomers according to theinvention have Bingham or plastic flow properties, or complexviscosities, that prevent flow of the coating layer into the intersticesof the fabric under the influence of gravity or capillary action.Sufficient pressure must be applied to the elastomer to create stress inexcess of the yield stress of the Bingham or plastic flow. The magnitudeand duration of the pressure must also create a shear stress sufficientto cause viscous flow into the particular geometry of the cavities inthe fabric. The duration of the pressure applied by blade 55 may notcause the desired level of penetration for some elastomers. For suchelastomers, the fabric may then pass between a pair of calender rolls 56that apply pressure of higher magnitude or longer duration. The durationof the pressure applied by the blade or roll may be only a fewmilliseconds at economical processing speeds, so the applied pressuremay be high. Alternatively, a lower pressure of longer duration cancause sufficient flow to fill the interstices of many useful fabrics. Asan example, a pressure of 250 psi applied for 2 minutes to the coatinglayer 54 having a complex viscosity less than 1.3×10E6 cps provides thedesired penetration of a typical envelope fabric 24 or tooth facingfabric 42.

Other penetration pressure applying methods include bagging andautoclaving the fabric 50 already treated with a coating layer 54. Thepressure can also be applied when the elastomeric product comprising thetreated fabric is vulcanized by keeping the vulcanization temperaturebelow T_(F) max for 2 to 5 minutes while the pressure is applied. Itshould be noted that if the material being coated with the elastomer isa cord, as opposed to a fabric, the pressure needed to fully encapsulatethe cord may be different than that required for treating the fabric.

Alternatively, as the elastomer is closer to solid state at roomtemperature, the elastomer may be calendered into a thin layer, which isthen pressed onto the fabric. This may be done in a batch process forfinite length fabric pieces or in a continuous process for rolls offabric, wherein the laminate is heated and pressure is applied theretoas the fabric travels along a predetermined path. Another method ofapplication of the elastomer is the use of a sheet or film extruder thatplaces the elastomer directly onto the fabric. Coating layer 54 appliedby calendering or extrusion can also be bagged and autoclaved or pressedduring vulcanization below T_(F) max to achieve penetration of thefabric interstices. Coating layer 54 can also be applied by conventionalspreading methods.

The viscosity of the liquid elastomer enables multiple layers of fabricto be impregnated at the same time. Multiple layers of identical fabricor layers of different fabric may be stacked up prior to impregnation.

After coating of the fabric 50, the fabric may be used immediately in amanufacturing process or cooled and stored. At room temperature, theliquid elastomer may have a solid state, permitting the fabric to bewound onto storage rolls.

The disclosed method provides for excellent rubber penetration into afabric or into the filaments of a cord. To enhance the bonding of therubber to the fabric or cord, the material may be pretreated with anadhesive, such as RFL (resorcinol formaldehyde latex), epoxy,isocyanate, or nylon adhesives to name a few. Such adhesives are wellknown in the art and may be applied by conventional methods.

The treatment method disclosed has the capability of yielding excellentpenetration and/or encapsulation of filaments, yarns, and/or fabrics andof yielding a high level of green tack of the filament, yarn, and/orfabric. The greater tack level will facilitate building of the greenproduct. In building belts in a grooved mold, the treated fabric may bepreformed to the shape of the grooves in the mold, and will have aminimum level of adherence in the mold. In building on a circularbuilding drum, the fabric layer will adhere to the adjacent layers. Dueto better adherence of the layers during building and curing, theuniformity of the product will increase.

For belts of the type illustrated in FIG. 2, conventionally, in somebelts, a plastic layer is applied to the outer surface of the fabriclayer, as an outermost layer, to reduce the coefficient of friction andprovide abrasion resistance. Such a plastic layer also prevents thetooth material, typically a high coefficient of friction material, fromflowing to the outer surface of the belt. By treating the fabric in themethod disclosed herein, the fabric is already coated and strikethroughof the tooth elastomer is pre-empted. Thus, the additional barrier layeris not required, reducing manufacturing complexity and costs.

While the method of treating fabric and manufacturing a product isdescribed in the context of manufacturing power transmission products,the method may be applied in the manufacture of other products such ashoses, air spring sleeves, tires, conveyor belts, or other reinforcedelastomeric articles.

1. A method for preparing a coated fabric which comprises (I) applying avulcanizable elastomer composition to a layer of fabric, wherein thevulcanizable elastomer composition is made by a method comprising thesteps of: (1) mixing a cross-linkable functionalized polyethylene withat least one cross-linkable liquid elastomer to form a non-reactiveextrudant, wherein the mixing occurs at a temperature in the range of10° F. above or below the melt point of the cross-linkablefunctionalized polyethylene, and wherein the non-reactive extrudantcontains from 20 to 80 parts per hundred of the cross-linkable liquidelastomer, (2) extruding the non-reactive extrudant, and (3) mixing theextrudent with at least one curing agent, wherein the mixing issufficient to form the vulcanizable elastomer, and wherein thevulcanizable elastomer has a complex dynamic viscosity of less than 5McP (5,000 N*s/m²) for at least 2 minutes at a maximum flow temperature;and (II) heating the layer of fabric having the vulcanizable elastomerapplied thereto to a temperature which is within the range of 200° F. to310° F. for at least 2 minutes to produce the coated fabric.
 2. Themethod of claim 1 wherein the layer of fabric is a non-woven fabric. 3.The method of claim 1 wherein the layer of fabric is a woven fabric. 4.The method of claim 1 wherein the layer of fabric is a knitted fabric.5. The method of claim 1 wherein the layer of fabric is a nylon fabric.6. The method of claim 1 wherein the layer of fabric is a polyesterfabric.
 7. The method of claim 1 wherein the layer of fabric is anaramid fabric.
 8. The method of claim 1 wherein the layer of fabric is arayon fabric.
 9. The method of claim 1 wherein the layer of fabric is acotton fabric.
 10. The method of claim 1 wherein the extrudant is formedinto the shape of strings or pellets.
 11. The method of claim 1 whereinthe cross-linkable functionalized polyethylene is a cross-linkableoxidized polyethylene.
 12. The method of claim 1 wherein thenon-reactive extrudant contains from 25 to 60 parts per hundred of thecross-linkable liquid elastomer.
 13. The method of claim 1 wherein thecross-linkable liquid elastomer is selected from the group consisting ofpolybutadiene rubber, nitrile rubber, hydrogenated nitrile rubber,styrene-butadiene rubber, neoprene rubber, butyl rubber, polyisoprenerubber, propylene rubber, carboxylated nitrile rubber, and EP(D)Mrubber.
 14. The method of claim 1 wherein the non-reactive extrudantcontains from 30 to 55 parts per hundred of the cross-linkable liquidelastomer.
 15. The method of claim 1 wherein the cross-linkable liquidelastomer is polybutadiene rubber.
 16. The method of claim 1 wherein thecross-linkable liquid elastomer is styrene-butadiene rubber.
 17. Themethod of claim 1 wherein the cross-linkable liquid elastomer ispolyisoprene rubber.
 18. The method of claim 1 wherein a non-reactiveextrudant is further comprised of an ethylene-propylene rubber and anenthylene-propylene-diene rubber.
 19. A method for preparing a coatedcord which comprises (I) applying a vulcanizable elastomer compositionto an uncoated cord, wherein the vulcanizable elastomer composition ismade by a method comprising the steps of: (1) mixing a cross-linkablefunctionalized polyethylene with at least one cross-linkable liquidelastomer to form a non-reactive extrudant, wherein the mixing occurs ata temperature in the range of 10° F. above or below the melt point ofthe cross-linkable functionalized polyethylene, and wherein thenon-reactive extrudant contains from 20 to 80 parts per hundred of thecross-linkable liquid elastomer, (2) extruding the non-reactiveextrudant, and (3) mixing the extrudent with at least one curing agent,wherein the mixing is sufficient to form the vulcanizable elastomer, andwherein the vulcanizable elastomer has a complex dynamic viscosity ofless than 5 McP (5,000 N*s/m²) for at least 2 minutes at a maximum flowtemperature; and (II) heating the cord having the vulcanizable elastomerapplied thereto to a temperature which is within the range of 200° F. to310° F. for at least 2 minutes to produce the coated cord.
 20. Themethod of claim 19 wherein the cross-linkable liquid elastomer isselected from the group consisting of polybutadiene rubber, nitrilerubber, hydrogenated nitrile rubber, styrene-butadiene rubber, neoprenerubber, butyl rubber, polyisoprene rubber, propylene rubber,carboxylated nitrile rubber, and EP(D)M rubber; and wherein thenon-reactive extrudant contains from 30 to 55 parts per hundred of thecross-linkable liquid elastomer.